chore(Scope): name the $watch deregistration function as

Author: IgorMinar

src/ng/rootScope.js

@@ -348,7 +348,7 @@ function $RootScopeProvider(){
         // the while loop reads in reverse order.
         array.unshift(watcher);
 
-        return function() {
+        return function deregisterWatch() {
           arrayRemove(array, watcher);
           lastDirtyWatch = null;
         };